1. Field of the Invention
The invention relates generally to actuating mechanisms for moving various components of a glassware forming machine through their respective operating cycles. More specifically, the invention relates to pneumatic actuating mechanisms, the velocity of which is controlled eletromechanically in one direction of cyclical operation. Still more specifically, the invention relates to pusher mechanisms for moving glassware containers through a predetermined arcuate path from a dead plate on to a moving conveyor.
2. Description of the Prior Art
Pusher mechanisms for moving glassware articles from a dead plate to a moving conveyor are well known in the prior art. These devices generally include a pneumatic pusher cylinder or head and a rotary actuator means for moving it through a predetermined arcuate path. In operation, each pusher cylinder piston is in a retracted position prior to the deposition of one or more glassware articles on a corresponding dead plate. Extension of the piston rod end by conventional pneumatic means positions fingers at the end of the piston rod near the glassware articles. Movement of the pusher cylinder through an arcuate path is an operating stroke which causes the fingers to contact the ware and move it outwardly through an angle of approximately 90.degree. onto a moving conveyor belt. The piston rod is then retracted and the pusher cylinder returned inwardly on a return stroke in the opposite arcuate direction to complete the cycle.
The arcuate outward velocity of the pusher cylinder is important since it must be slow enough at the start of the cycle so as not to make unstable or break the glassware upon contact with the fingers and subsequently fast enough to match the arcuate glassware velocity to the conveyor velocity.
In the prior art such pusher mechanisms are often mechanical devices where the pusher cylinder piston motion is caused pneumatically and the rotary motion of the pusher cylinder is provided through appropriate gearing from a common mechanical drive train. Each section of the glassware forming machine has a separate pusher mechanism associated with it although each mechanism is driven by a single motor via a common drive shaft. These prior art mechanical devices prove troublesome from the point of view of adjusting the timing of the individual pusher mechanisms to the operation of other mechanical components of the glassware forming machine. Moreover, the velocity profile of the arcuate movement of each pusher cylinder is difficult to adjust because it depends upon the profile of a cam associated with each mechanism. Selection of a different velocity profile for the pusher mechanism of one or more sections requires replacement of the associated cam which means stopping the entire conveyor.
More recently, electronic pusher mechanisms have been produced where each pusher mechanism may be driven independently of the others according to a predetermined velocity profile by an electric motor controlled by a common control means. In some such prior art units several velocity profiles may be stored in memory and recalled at will. Examples of such prior art electronic pushers are shown in U.S. Pat. Nos. 4,203,752 and 4,313,750.
Each of these prior art electronic pushers requires a relatively large electric motor in driving connection with the pusher cylinder in order to control its arcuate movement in both directions (both inward and outward arcuate strokes). Because the pusher cylinder is a relatively massive component these electric motors are necessarily large and require high torque, thus making these prior art electric pusher mechanisms costly and inefficient. Moreover, the return stroke of the pusher cylinder in such prior art electric pushers is constrained by the ability of the electric motor to move the relatively massive cylinder head.
Accordingly, it is an object of this invention to produce an actuating apparatus for cyclically moving a member through a predetermined arcuate path. It is a further object to produce an actuating apparatus having a fluidic driving means and an electromechanical control means. Note that the term "fluidic" as used herein means either pneumatic or hydraulic. It is still another object of this invention to produce such an apparatus wherein the velocity of the driving means is controlled. A further object of this invention is to produce a pusher mechanism embodying the principles of the foregoing actuating apparatus in order to move a pusher cylinder through a predetermined arcuate path.
Furthermore, prior art pusher mechanisms, regardless of how the rotary actuator is driven, generally supply pushout and retract air to the pusher cylinder via two separate fluidic or air passages. These passages are provided in the base portion upon which the turntable (supporting the pusher cylinder) is mounted and communicate with ports in the turntable at predetermined angular positions thereof. Consequently, the pushout and retract functions are restricted to occur only at certain points in the pusher mechanism's operating cycle.
It is, therefore, another object of this invention to produce a pusher mechanism wherein the pusher cylinder may be actuated at any desired point in the operating cycle thereof.